Expression of IroN, the salmochelin siderophore receptor, requires mRNA activation by RyhB small RNA homologues

Roberto Balbontín, Nicolás Villagra, Maria Pardos de la Gándara, Guido Mora, Nara Figueroa-Bossi, Lionello Bossi

Producción científica: Contribución a una revistaArtículorevisión exhaustiva

17 Citas (Scopus)

Resumen

The iroN gene of Salmonella enterica and uropathogenic Escherichia coli encodes the outer membrane receptor of Fe3+-bound salmochelin, a siderophore tailored to evade capture by the host's immune system. The iroN gene is under negative control of the Fur repressor and transcribed under iron limiting conditions. We show here that transcriptional de-repression is not sufficient to allow iroN expression, as this also requires activation by either of two partially homologous small RNAs (sRNAs), RyhB1 and RyhB2. The two sRNAs target the same sequence segment approximately in the middle of the 94-nucleotide 5′ untranslated region (UTR) of iroN mRNA. Several lines of evidence suggest that base pair interaction stimulates iroN mRNA translation. Activation does not result from the disruption of a secondary structure masking the ribosome binding site; rather it involves sequences at the 5′ end of iroN 5′ UTR. In vitro 'toeprint' assays revealed that this upstream site binds the 30S ribosomal subunit provided that RyhB1 is paired with the mRNA. Altogether, our data suggest that RyhB1, and to lesser extent RyhB2, activate iroN mRNA translation by promoting entry of the ribosome at an upstream 'standby' site. These findings add yet an additional nuance to the polychromatic landscape of sRNA-mediated regulation.

Idioma originalInglés
Páginas (desde-hasta)139-155
Número de páginas17
PublicaciónMolecular Microbiology
Volumen100
N.º1
DOI
EstadoPublicada - 1 abr. 2016

Áreas temáticas de ASJC Scopus

  • Microbiología
  • Biología molecular

Huella

Profundice en los temas de investigación de 'Expression of IroN, the salmochelin siderophore receptor, requires mRNA activation by RyhB small RNA homologues'. En conjunto forman una huella única.

Citar esto